Struct CommandMessage 

pub struct CommandMessage {
    pub transaction_id: u32,
    pub timecode: i64,
    pub topic: String,
    pub message_type: MessageType,
    pub data: Value,
    pub crc: u32,
    pub success: bool,
    pub error_message: String,
}

CommandMessage is the unified message format for all IPC communication.

This struct serves as both request and response, with message_type indicating the role and success/error_message fields populated for responses.

Example: Creating a read request

use mechutil::ipc::{CommandMessage, MessageType};

let msg = CommandMessage::read("modbus.server1.holding_0");
assert_eq!(msg.message_type, MessageType::Read);

Example: Creating a response

use mechutil::ipc::CommandMessage;
use serde_json::json;

let mut response = CommandMessage::response(42, json!({"value": 123}));
assert!(response.success);

Fields

transaction_id: u32

Unique identifier to match responses to requests. Generated automatically if not specified.

timecode: i64

Timestamp in milliseconds since UNIX epoch. Set automatically on message creation.

topic: String

Fully-qualified topic name (FQDN). Format: “domain.subtopic.path” e.g., “ads.plc1.GM.stData”

message_type: MessageType

The type/purpose of this message.

data: Value

The payload data.

• For requests: arguments/parameters
• For responses: result data

crc: u32

CRC32 checksum of the message (optional, for integrity verification).

success: bool

Whether the operation was successful (for responses).

error_message: String

Error message if the operation failed (for responses).

Implementations

impl CommandMessage

pub fn new() -> Self

Create an empty CommandMessage with auto-generated transaction_id and timecode.

pub fn request(topic: &str, data: Value) -> Self

Create a request message with the specified topic and data.

pub fn read(topic: &str) -> Self

Create a read request for the specified topic.

pub fn write(topic: &str, data: Value) -> Self

Create a write request for the specified topic with data.

pub fn subscribe(topic: &str) -> Self

Create a subscribe request for the specified topic.

pub fn unsubscribe(topic: &str) -> Self

Create an unsubscribe request for the specified topic.

pub fn response(transaction_id: u32, data: Value) -> Self

Create a successful response to a request.

pub fn error_response(transaction_id: u32, error: &str) -> Self

Create an error response to a request.

pub fn broadcast(topic: &str, data: Value) -> Self

Create a broadcast message with the specified topic and data.

pub fn heartbeat() -> Self

Create a heartbeat message.

pub fn control(topic: &str, data: Value) -> Self

Create a control message.

pub fn with_transaction_id(self, id: u32) -> Self

Set the transaction ID.

pub fn with_topic(self, topic: &str) -> Self

Set the topic.

pub fn with_data(self, data: Value) -> Self

Set the data payload.

pub fn with_success(self, data: Value) -> Self

Set as successful with data.

pub fn with_error(self, error: &str) -> Self

Set as error with message.

pub fn set_success(&mut self, data: Value)

Set successful result on this message.

pub fn set_error(&mut self, error: &str)

Set error result on this message.

pub fn into_response(self, data: Value) -> Self

Convert this request into a successful response.

pub fn into_error_response(self, error: &str) -> Self

Convert this request into an error response.

pub fn is_response(&self) -> bool

Check if this is a response message.

pub fn is_broadcast(&self) -> bool

Check if this is a broadcast message.

pub fn is_heartbeat(&self) -> bool

Check if this is a heartbeat message.

pub fn is_request(&self) -> bool

Check if this is a request (Read, Write, Subscribe, Unsubscribe, or Request).

pub fn domain(&self) -> &str

Get the domain (first segment of the topic).

pub fn subtopic(&self) -> String

Get the subtopic (everything after the first dot), normalized to lowercase.

pub fn compute_crc(&self) -> u32

Compute CRC32 of the message content.

pub fn update_crc(&mut self)

Update the CRC field with the computed value.

pub fn verify_crc(&self) -> bool

Verify that the CRC matches the message content.

Trait Implementations

impl Clone for CommandMessage

fn clone(&self) -> CommandMessage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CommandMessage

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CommandMessage

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for CommandMessage

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for CommandMessage

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.